Holder says the Justice Department is reviewing the matter, including letters from New Jersey officials complaining that they were kept in the dark about the surveillance.

The attorney general made the remarks at a subcommittee hearing of the Senate Appropriations Committee when asked by Sen. Frank Lautenberg, D-N.J., how a law enforcement agency could spy on another state’s residents without notifying authorities.

“I don’t know,” Holder replied. “We are in the process of reviewing the letters that have come in expressing concerns about those matters.”

“At least what I’ve read publicly, and again, just what I’ve read in the newspapers, is disturbing,” Holder said. “And these are things that are under review at the Justice Department.”

Holder said he has also spoken to New Jersey Gov. Chris Christie, who strongly emphasized his concerns about the surveillance program.

The attorney general said that at a reception several days ago, Christie “expressed to me the concerns that he had” and that he “has now publicly expressed his concerns as only he can.”

Christie has criticized the NYPD for what he and other New Jersey officials have described as less than full coordination and disclosure to them of what was going on.

Holder didn’t say whether he was more concerned about the lack of coordination or the surveillance itself.

Meanwhile, an interfaith news conference was held in Jersey City Thursday to denounce the NYPD’s surveillance program.

“An investigation will definitely shed a lot of light on who knew what and where and who should have had the responsibility to carry the admission forward and who should have stopped it and what have you,” said Mohamad El Filali, executive director of the Islamic Center in Passaic County.

He wasn’t yet saying if he was considering a lawsuit, El Filali thinks the NYPD’s surveillance of Muslims and businesses violates their civil rights by investigating across the Hudson River.

“There is no justification,” he said.

“If you don’t stand up with your brothers and sisters of other faiths, what happens to them will eventually happen to you,” said Father Phil Latronico from the Newark Archdiocese, among several clergy who spoke out.

State attorney general spokesman Paul Loriquet says what they find will determine their actions at that point.

On Wednesday, the head of the Newark FBI said the NYPD’s monitoring of Muslims in the Garden State has hindered the feds’ ability to gather counter terrorism intelligence.

“What we’re seeing now with the uproar that is occurring in New Jersey is that we’re starting to see cooperation pulled back. People are concerned that they’re being followed. People are concerned that they can’t trust law enforcement,” said FBI Newark special agent in charge Michael Ward.

(TM and Copyright 2012 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2012 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)